Add version header.

src/CMakeLists.txt

@@ -1,5 +1,9 @@
 include(GNUInstallDirs)
 
+# Write version in header.
+configure_file ("version.hpp.in"
+  "${PROJECT_BINARY_DIR}/version.hpp" @ONLY)
+
 add_library(${PROJECT_NAME})
 
 file(GLOB_RECURSE sources_lib *.cpp)

src/version.hpp.in

@@ -0,0 +1,15 @@
+#ifndef MASTODONPP_VERSION_HPP
+#define MASTODONPP_VERSION_HPP
+
+#include <string_view>
+
+namespace mastodonpp
+{
+
+using std::string_view;
+
+static constexpr string_view version = "@PROJECT_VERSION@";
+
+} // namespace mastodonpp
+
+#endif // MASTODONPP_VERSION_HPP